Low back pain, an Institute of Medicine priority condition for comparative effectiveness research, is of major public health importance. It is one of the most common reasons for physician visits and an important cause of functional limitation and disability. Imaging is frequently performed as part of the diagnostic evaluation and is an important contributor to the cost of back pain care, which totaled more than $86 billion in 2005. It is well known that, even without back pain, magnetic resonance (MR) imaging of the lumbar spine frequently reveals findings such as disc desiccation or bulging. Patients and their providers may attribute greater importance to these findings, which are often age-related, than they should, because they do not have an appropriate frame of reference in which to interpret the findings. These incidental findings may initiate a cascade of events leading possibly even to surgery, without improving patient outcomes. We propose a pragmatic, randomized controlled trial (RCT) to determine the effectiveness of inserting epidemiological benchmarks into imaging reports at reducing subsequent tests and treatments. Our rationale is that providing a context for both physicians and patients to better interpret imaging findings may reduce concern about incidental findings and reduce unnecessary further diagnostic tests and treatments. Our intervention is simple, inexpensive and easy to deploy. We propose an efficient, novel, cluster randomized design referred to as a stepped wedge design, permitting longitudinal comparisons while controlling for temporal trends. As called for in the Request for Applications, we plan to passively collect primary outcome measures of healthcare utilization both pre- and post-intervention, using robust electronic medical records at our participating sites. We hypothesize that for patients of primary care providers, inserting epidemiological benchmarks in lumbar spine imaging reports will reduce subsequent diagnostic and therapeutic interventions, including MR and CT, opioid prescriptions, spinal injections and surgery. The rationale is that the epidemiologic data may provide a context for both physicians and patients to better interpret imaging findings. The long-term public health significance is high. Not only may this simple, inexpensive intervention substantially reduce unnecessary and expensive care for back pain; thee intervention can easily be generalized to all diagnostic tests, and could become the dominant paradigm for communicating diagnostic information.